Companion AI

Companion AI are programs that you write or talk to as if with a friend or partner. The term “companion” refers to exactly what these apps aim for. They usually have a name, an appearance, and a defined character. Unlike a search engine, they aren’t meant to solve tasks, but to provide company. To do this, they remember past conversations: the user’s name, their dog, the argument from last week. Well-known examples are Replika, Character.AI, and the companion figures in Meta's apps.

Loneliness as a business model

Companion AI is the first major area in which people voluntarily pay money for pure entertainment with software. Character.AI reported at times over 20 million monthly users, many of them younger than 25. The average session duration is significantly longer than that of normal chat assistants. For investors, this is a strong signal: long dwell time means stable subscription revenue.

At the same time, hardly any AI area is as controversial. Critics point out that the apps are optimized to make users come back. A companion that agrees, flatters, and never contradicts can create emotional dependency. Following lawsuits by parents in the US, several providers came under pressure because minors had held disturbing or sexualized conversations.

That’s why this area is also of interest for regulation. The US state of California obligated providers in 2025 to regularly point out that the conversation partner is a machine. In the EU, the AI Act, Europe’s AI law, applies with a similar labeling requirement. Anyone evaluating such stocks or startups must factor in this legal risk.

What creates the illusion of a relationship

Technically, a language model is behind it. That is a program that has learned from huge amounts of text which word is likely to come next. Such a model alone has no personality. The character is created through a hidden preamble called a system prompt: an instruction like “Your name is Mira, you are 24, warm-hearted, and like to ask follow-up questions.” This text is invisibly placed before the conversation with every request.

The second component is a memory. The model itself forgets everything after the conversation. So the app stores important statements from the user in a database and reinserts matching excerpts in later conversations. This makes it seem as though the character remembers. In reality, it re-reads notes about the user every time.

A common misconception: that the character has developed feelings for the user. It generates sentences that fit an attentive role – nothing more. Some providers additionally fine-tune their models using ratings from real users so that responses seem even more pleasant. This very fine-tuning reinforces the tendency toward flattery, because agreement is rated better than contradiction.

From Replika to the game NPC

Companion AI is most visible in dedicated apps. Replika sells subscriptions for romantic roles, Character.AI offers thousands of user-built characters, from study partners to fantasy characters. In China, Xiaoice has been active for years with hundreds of millions of contacts. Prices are typically around ten to twenty euros per month.

Beyond that, the technology is migrating into existing products. Video games are testing side characters that respond freely instead of reciting scripted lines. Smart glasses and speakers are getting voices with character. Care facilities are also testing conversation robots against loneliness among the elderly, so far with mixed results.

The distinction from the assistant is important. An assistant like ChatGPT is designed for tasks: summarizing, coding, researching. A Companion AI is designed for bonding and lives off continuation. In the news, both often appear under the word “chatbot” – but the difference in business model is substantial.